Anti‐ribosomal P protein: a novel antibody in autoimmune hepatitis

Abstract Background Autoantibodies to ribosomal P proteins (anti‐rib P) are specific serological markers for systemic lupus erythematosus ( SLE ) and are associated with liver involvement in this disease. The similarity in autoimmune background between autoimmune hepatitis ( AIH ) and SLE ‐associated hepatitis raises the possibility that anti‐rib P antibodies might also have relevance in AIH . Aims To evaluate the frequency and clinical significance of anti‐rib P antibodies in a large AIH cohort. Methods Sera obtained at diagnosis of 96 AIH patients and of 82 healthy controls were tested for IgG anti‐ribosomal P protein by ELISA . All of the sera were also screened for other lupus‐specific autoantibodies, three patients with the presence of anti‐ds DNA ( n = 1) and anti‐Sm ( n = 2) were excluded. Results Moderate to high titres (>40 U) of anti‐rib P antibody were found in 9.7% (9/93) of the AIH patients and none of the controls ( P = 0.003). At presentation, AIH patients with and without anti‐rib P antibodies had similar demographic/clinical features, including the frequency of cirrhosis (44.4 vs. 28.5%, P = 0.44), hepatic laboratorial findings ( P > 0.05). Importantly, at the final observation (follow‐up period 10.2 ± 4.9 years), the AIH patients with anti‐rib P had a significantly higher frequency of cirrhosis compared with the negative group (100 vs. 60%, P = 0.04). Conclusion The novel demonstration of anti‐rib P in AIH patients without clinical or laboratory evidence of SLE suggests a common underlying mechanism targeting the liver in these two diseases. In addition, this antibody appears to predict the patients with worse AIH prognoses.